A drive train generally corresponds to a plurality of devices used to transmit energy generated by an engine to drive wheels, and includes an engine, a clutch, a transmission, a drive shaft, a propeller shaft, a differential gear, and drive wheels. In a drive train testing system, the durability performance or the quality of a drive train is evaluated while an appropriate load torque is applied to an output shaft in a manner so that the transmission is actually driven by an engine and a dynamometer connected to an output shaft thereof is subjected to an electric inertia control.
In many cases, in the electric inertia control employed in such a testing system, only a single inertia amount corresponding to a vehicle inertia moment can be set as shown in, for example, Patent Document 1. This simulation model is assumed under the condition that the vehicle normally travels on a road surface while a tire actually grips the road surface without any slip. However, in reality, there are road surface conditions, such as a snowy surface or an icy surface on which the tire easily slips. In the testing system shown in Patent Document 1, it is difficult to reproduce a state in which the tire slips on such a road surface.
Patent Document 2 discloses a technique for calculating load torque based on a dynamic characteristic model of a vehicle equipped with a drive train. The dynamic characteristic model includes a slip model that calculates the longitudinal force acting on the vehicle based on the slip ratio of the tire and the perpendicular load acting on the vehicle. Accordingly, a load torque is generated by a dynamometer in consideration of the slip behavior of the tire.
[Patent Document 1] Japanese Unexamined Patent Application, Publication No. 2009-74834
[Patent Document 2] Japanese Unexamined Patent Application, Publication No. 2005-61889